Machining method of thin-wall ring part with eccentric structure

Abstract

The invention discloses a machining method for a thin-wall ring part with an eccentric structure, and belongs to the technical field of aero-engine part machining. The machining method comprises the steps that S100, a clamp is prepared, and a verification hole and a plurality of positioning holes are machined in the clamp; s200, the part is fixed to a clamp, a plurality of positioning datum holes are formed in the part, the circle centers of the positioning datum holes are distributed on a circle with the rotation center of the part as the circle center, the positioning datum holes of the part are aligned with the positioning holes of the clamp, and the geometric center of the target machining area of the part coincides with the rotation center of the clamp; s300, the target machining area is machined according to preset parameters; and S400, metering detection is conducted, and the actual diameter of the target machining area is judged according to the difference value between the target machining area of the part and the metering value of the hole wall of the verification hole of the clamp. The problem that an eccentric structure is difficult to position, align and measure is solved.

Description

Technical Field

[0001] This invention relates to the field of machining technology for aero-engine components, specifically a machining method for thin-walled ring-shaped parts with an eccentric structure. Background Technology

[0002] Thin-walled ring-shaped parts are a common structural form in high-end equipment such as aero-engines. They are characterized by thin walls, complex structures, and poor rigidity, making them prone to deformation during machining and difficult to control in terms of dimensions. In certain applications, to meet functional requirements or compensate for structural interference, it is necessary to perform eccentric machining on a specific area of ​​these parts. For example, when the overall rotation center deviates from the center of the target arc segment, directional grinding or adjustment of the inner hole is required.

[0003] Taking the free turbine casing of an aero-engine as an example, some models experience turbine blade and inner bore scraping during service, requiring eccentric grinding correction of the inner bore. This involves offsetting the target arc segment relative to the original rotation center in a specific direction to increase the local clearance and avoid interference. However, existing machining processes face the following key technical challenges when dealing with this type of eccentric machining task:

[0004] The eccentricity direction is difficult to determine: the target arc segment is usually deviated from the original center by a precise angle, but since the part itself does not have obvious angular reference markings, it is difficult to accurately establish a reference coordinate system for the eccentricity direction during machining; the eccentricity position is difficult to achieve: the eccentric axial offset is generally small, and if the spatial correspondence between the fixture rotation center and the target machining center cannot be established, the eccentric axis cannot be accurately converted to the spindle center, resulting in positioning failure; as a result, in the traditional alignment method, it is impossible to obtain the rotation center of the target machining hole through the original inner hole, and the machining reference is difficult to establish. Summary of the Invention

[0005] This invention provides a method for processing thin-walled ring-shaped parts with an eccentric structure, in order to solve the technical problem of the difficulty in positioning and processing thin-walled ring-shaped parts with an eccentric structure.

[0006] According to one aspect of the present invention, a method for machining a thin-walled ring-shaped part with an eccentric structure is provided for machining a part in which the center of rotation is eccentric to the geometric center of the target machining area, comprising:

[0007] S100, prepare a fixture, process a verification hole and multiple positioning holes on the fixture, the verification hole is coaxial with the rotation center of the fixture, and the diameter of the verification hole is consistent with the target diameter D of the target processing area, the centers of the multiple positioning holes form a fitting circle, the center of the fitting circle is offset from the rotation center of the fixture, and the offset value is the same as the offset value between the rotation center of the part and the geometric center of the area to be processed.

[0008] S200, fix the part on the fixture. The part is provided with multiple positioning reference holes. The centers of the multiple positioning reference holes are distributed on a circle with the rotation center of the part as the center. Align the positioning reference holes of the part with the positioning holes of the fixture so that the geometric center of the target machining area of ​​the part coincides with the rotation center of the fixture.

[0009] S300 processes the target processing area using preset parameters;

[0010] S400 performs dial indicator testing, determining the actual diameter of the target machining area based on the difference between the dial indicator value of the target machining area and the calibration hole wall of the fixture.

[0011] Optionally, in step S400, the difference between the target machining area of ​​the part and the dial indicator value of the calibration hole wall of the fixture is used to determine the target machining area.

[0012] The actual diameter of the marked machining area includes the following steps:

[0013] S410, zero the dial indicator by contacting the dial indicator head with the inner wall of the calibration hole;

[0014] S420, move the dial indicator along the fixture axis until the dial indicator head contacts the target machining area of ​​the part, and read the dial indicator reading A;

[0015] S430, calculate the actual diameter D1 of the target processing area according to the formula D1=D+2A.

[0016] Optionally, in step S200, fixing the part to the fixture includes the following steps:

[0017] S210, Align the part positioning reference hole with the fixture positioning hole;

[0018] S220, a positioning pin is inserted into the positioning reference hole of the part and the positioning hole of the fixture. The mating part between the positioning pin and the positioning hole is a cylindrical surface.

[0019] The mating surface between the locating pin and the locating reference hole is a conical surface;

[0020] S230 uses multiple locking screws to lock the parts onto the fixture.

[0021] Optionally, step S230 includes the following steps:

[0022] S231, Perform dial gauge measurement on the end face of the part before locking;

[0023] S232, multiple screws are tightened in a symmetrical tightening sequence;

[0024] S233, after locking, measure the end face of the part again using a dial indicator and compare the measurement difference before and after locking. If the difference is not greater than the preset maximum allowable end face deformation, proceed to the next step.

[0025] Optionally, in step S232, the multiple screws are tightened in a symmetrical locking sequence. This means that, with the rotation center of the clamp as the reference center, a pair of screws at mutually symmetrical positions are selected and tightened in sequence. Then, the tightening is gradually extended to the unclamped screws in an evenly distributed manner until all screws are tightened in a symmetrical sequence, so as to ensure that the clamping force is evenly distributed along the circumference.

[0026] Optionally, in step S300, the processing of the target processing area includes multiple stages, namely roughing, semi-finishing and finishing. The feed rate and part rotation speed parameters of roughing, semi-finishing and finishing decrease sequentially. Throughout the entire process of step S300, the grinding wheel linear speed remains constant.

[0027] Optionally, in step S200, one positioning reference hole of the part is marked as an angular reference hole, and one positioning hole of the fixture is marked as an angular reference hole. The angular reference holes of the part and the fixture are coaxial to achieve angular offset matching.

[0028] Optionally, after fixing the part on the fixture in step S200 and before processing in step S300, the method further includes: aligning the runout of the calibration hole of the fixture to control the runout of the calibration hole within a preset allowable range.

[0029] Optionally, in step S300, after finishing to the target size, the feed is stopped and grinding continues for a preset time.

[0030] Optionally, the fixture has calibration marks on the calibration hole for use with a dial indicator for drag testing.

[0031] In summary, this application includes at least one of the following beneficial technical effects:

[0032] This solution establishes a spatial correspondence between the jig's rotation center and the geometric center of the eccentric target area, achieving precise positioning and conversion of the machining datum for thin-walled ring-shaped parts with eccentric structures during machining. Specifically, in step S100, by machining a verification hole coaxial with the rotation center and a set of eccentrically arranged positioning holes on the jig, an offset coordinate system capable of eccentric mapping within the jig is constructed. The offset of the center of the fitted circle relative to the jig's rotation center is completely consistent with the offset of the target machining area in the part relative to the overall rotation center. Next, in step S200, the part with multiple positioning datum holes is mounted onto the jig, ensuring a one-to-one correspondence with the positioning holes. Alignment is achieved through angular datum hole alignment, ensuring the eccentric structure of the part is accurately converted to the spindle rotation center position after jig assembly. This solves the problem of inaccurate alignment in traditional machining due to the target area not being at the original rotation center. Step S300, relying on the new machining datum established by the jig, enables machining operations on the eccentric area. Finally, by using a dial indicator in step S400 for testing, and with the calibration hole in the fixture as a reference, the actual diameter of the eccentric arc segment was effectively measured, further closing the process chain from positioning and machining to measurement. The overall solution, through offset construction, datum reconstruction, and measurement linkage, solved the problems of difficult positioning, alignment, and measurement of eccentric structures, making the precision machining of thin-walled ring-shaped parts possible.

[0033] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0034] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0035] Figure 1 This is a schematic cross-sectional view of the fixture of the present invention;

[0036] Figure 2 This is a top view of the fixture of the present invention;

[0037] Figure 3 This is a top view of the part of the present invention;

[0038] Figure 4 This is a cross-sectional view of the part of the present invention.

[0039] Legend:

[0040] 1. Fixture; 2. Verification hole; 3. Positioning hole; 4. Positioning reference hole; 5. Positioning pin; 6. Locking screw. Detailed Implementation

[0041] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0042] The following is in conjunction with the appendix Figure 1-4 This application will be described in further detail.

[0043] This invention aims to solve the existing challenges in machining thin-walled ring-shaped parts with eccentric structures, particularly addressing the following key issues: First, the eccentric direction is difficult to establish accurately. Due to the spatial offset between the target machining area and the overall rotation center of the part, and the lack of a stable angular reference, traditional machining methods struggle to reliably convert and match the eccentric direction. Second, the eccentric center is difficult to align stably. When the target machining area is not concentric with the original inner hole, the rotation center of the eccentric area cannot be aligned using conventional methods, and a coaxial relationship cannot be established between the machining spindle and the actual machining area, leading to large machining errors or even making machining impossible. Third, measuring the eccentric arc segment is difficult. When the area to be machined is a locally eccentric arc segment, traditional through-hole gauges or standard coordinate measurement methods cannot be used for effective detection, and the machining process lacks a real-time feedback control mechanism. In summary, a systematic machining scheme that integrates fixture structure, spatial offset mapping, measurement reference conversion, and machining path control is needed to achieve high-precision, controllable, and repeatable machining of eccentric thin-walled ring-shaped parts.

[0044] Reference Figure 1 and Figure 2 To achieve the above objectives, the present invention provides a machining method for thin-walled ring-shaped parts where the center of rotation is eccentric to the geometric center of the target machining area. The technical solution includes the following steps:

[0045] S100, prepare fixture 1, process verification hole 2 and multiple positioning holes 3 on fixture 1, verification hole 2 is coaxial with the rotation center of fixture 1, and the diameter of verification hole 2 is consistent with the target diameter D of the target processing area, the centers of multiple positioning holes 3 form a fitting circle, the center of the fitting circle is offset from the rotation center of fixture 1, and the offset value is the same as the offset value between the rotation center of the part and the geometric center of the area to be processed;

[0046] S200, fix the part on the fixture 1. The part is provided with multiple positioning reference holes 4. The centers of the multiple positioning reference holes 4 are distributed on a circle with the rotation center of the part as the center. Align the positioning reference holes 4 of the part with the positioning holes 3 of the fixture 1 so that the geometric center of the target machining area of ​​the part coincides with the rotation center of the fixture 1.

[0047] S300 processes the target processing area using preset parameters;

[0048] S400, perform dial indicator testing, and determine the actual diameter of the target machining area based on the difference between the dial indicator value of the target machining area of ​​the part and the wall value of the calibration hole 2 of fixture 1.

[0049] This solution effectively solves several key problems in the machining of eccentric thin-walled ring-shaped parts by introducing a fixture 1 structure with offset setting function and a corresponding clamping and positioning method. First, the fixture 1 has multiple positioning holes 3 arranged around a fitted circle. The center of the fitted circle is offset angularly and radially relative to the rotation center of the fixture 1. The offset value is consistent with the spatial offset between the rotation center of the part and the geometric center of the target machining area. This, combined with the alignment of the angular reference holes on the part with the calibration holes of the fixture 1, achieves precise conversion and establishment of the eccentric direction. By ensuring that the multiple positioning reference holes 4 on the part correspond one-to-one with the positioning holes 3 of the fixture 1, and by aligning the geometric center of the eccentric area with the rotation center of the fixture 1, a stable machining coordinate system is established. This solves the problem of the eccentric center not being coaxial, ensuring precise positioning of the target machining area on the machining spindle. Finally, by setting a calibration hole 2 coaxial with the spindle on the fixture 1, and using the inner wall of the calibration hole 2 as the measurement reference, and combining it with a dial indicator for drag testing, indirect measurement and dimensional evaluation of the eccentric arc segment were realized. This broke through the measurement blind spot of the local eccentric structure that traditional measuring tools cannot cover, and formed an operable real-time feedback control mechanism, which effectively supported the high-precision machining of eccentric structure parts.

[0050] Specifically, the offset in step S100 includes two dimensions: angular offset and radial distance offset. Together, they constitute a complete eccentricity description that maps the geometric center of the target machining area of ​​the part from the original rotation center to the rotation center of fixture 1. The angular offset refers to the circumferential angle of the center of the fitted circle relative to the rotation center of fixture 1, used to match the directional attributes of the part's eccentric structure. The radial distance offset refers to the linear distance between the center of the fitted circle and the rotation center of fixture 1, used to simulate the actual eccentricity of the target machining area of ​​the part relative to the overall rotation center.

[0051] Reference Figure 2 and Figure 3In one embodiment, firstly, a calibration hole 2, coaxial with the rotation center of fixture 1, is designed on fixture 1. The diameter of this hole is 237.67 mm, used for subsequent dial indicator measurements and also as a calibration benchmark for machining accuracy. Subsequently, three φ6 (+0.012, 0) positioning holes 3 are machined on fixture 1, with their centers evenly distributed around a fitted circle. The center of this fitted circle has a specific offset relative to the rotation center of fixture 1; specifically, the radial offset distance is 0.15 mm in a direction deviating 30° counterclockwise. This offset parameter is determined based on the design requirements of the part body and is exactly equal to the spatial offset of the geometric center of the target machining area of ​​the part relative to the original rotation center.

[0052] In use, the workpiece is equipped with three corresponding φ7 (+0.047, +0.025) positioning reference holes 4, one of which is marked with a "0" as an angular reference hole. The fixture 1 is also marked with a "0" hole (1#) corresponding to it. When the "0" hole of the workpiece is aligned with the "0" hole of the fixture 1, the geometric center of the target eccentric arc segment on the workpiece is automatically transformed to the rotation center of the fixture 1, achieving structural coaxial coincidence. This means that the spindle center around which subsequent machining revolves corresponds to the rotation center of the eccentric arc segment, solving the problem of establishing a machining coordinate system due to the eccentric position in traditional machining.

[0053] Reference Figure 1 and Figure 4 In one embodiment, step S200, fixing the part to the fixture 1, includes the following steps:

[0054] S210, Align the part positioning reference hole 4 with the fixture 1 positioning hole 3;

[0055] S220, a positioning pin 5 is inserted into the positioning reference hole 4 of the part and the positioning hole 3 of the fixture 1. The mating part of the positioning pin 5 and the positioning hole 3 is a cylindrical surface, and the mating surface of the positioning pin 5 and the positioning reference hole 4 is a conical surface.

[0056] S230, multiple locking screws 6 are used to lock the part onto the fixture 1.

[0057] S210 first involves aligning the multiple positioning reference holes 4 on the part with the pre-designed and arranged positioning holes 3 on the fixture 1 one-to-one. Special attention must be paid to the alignment of the angular reference holes to ensure accurate establishment of the eccentric direction. Next, S220 is executed, where positioning pins 5 are sequentially inserted into the aligned positioning holes 3 of the fixture 1 and the positioning reference holes 4 of the part, completing the connection of the positioning structure. These positioning pins 5 have a two-section structure: the part that mates with the hole in the fixture 1 is a cylindrical structure to ensure the stability and repeatability of the positioning direction, while the part that mates with the hole in the part is a conical structure with an automatic alignment function, eliminating gaps caused by manufacturing errors and achieving a gapless fit, thereby further improving the overall clamping accuracy and consistency. Through this connection method, the geometric center of the target machining area of ​​the part can be stably aligned with the rotation center of the fixture 1, establishing accurate geometric and motion references for subsequent machining, avoiding offset or runout during machining, and significantly improving the reliability of clamping and positioning.

[0058] In one implementation, step S230 includes the following steps:

[0059] S231, Perform dial gauge measurement on the end face of the part before locking;

[0060] S232, multiple screws are tightened in a symmetrical tightening sequence;

[0061] S233, after locking, measure the end face of the part again using a dial indicator and compare the measurement difference before and after locking. If the difference is not greater than the preset maximum allowable end face deformation, proceed to the next step.

[0062] Step S230, through a refined screw tightening process, ensures that the thin-walled part will not deform due to uneven force during clamping, guaranteeing the consistency of the part's state before and after processing. Specifically, in S231, firstly, in the un-tightened state, a dial indicator is used to measure the full circumference of the part's end face, recording the baseline runout value as a reference for subsequent deformation judgment; then, in S232, multiple screws are gradually tightened in a symmetrical locking sequence, that is, with the rotation center of fixture 1 as the center of symmetry, the screws distributed in pairs are tightened first, and the tightening is gradually extended to other directions to avoid warping or misalignment of the part caused by local stress concentration; finally, in S233, the end face of the part is measured again with a dial indicator and compared with the data in S231. If the runout difference before and after tightening is not greater than the preset maximum allowable end face deformation, it indicates that the clamping process has not caused significant deformation, and the formal processing stage can begin.

[0063] Specifically, in step S232, to ensure that the thin-walled ring-shaped parts are subjected to balanced force during clamping and to avoid end face warping or misalignment, multiple locking screws 6 are tightened gradually in a symmetrical locking sequence. This method uses the rotation center of the fixture 1 as a symmetrical reference center, preferentially selecting a pair of screws symmetrically positioned on the circumference for initial pre-tightening, and then extending to the remaining untightened areas at equal angular intervals, completing the symmetrical tightening of the remaining screws group by group.

[0064] In this embodiment, the clamp 1 is equipped with 27 locking screws 6, evenly distributed around the circumference. During tightening, an alternating, opposite-side advancing method is used. First, screw number 1 and its symmetrically numbered screws are tightened, then the symmetrically numbered positions "1–15", "2–16", "3–17", etc., are advanced sequentially, gradually expanding to the entire circumference to create a symmetrical and balanced preload distribution. The tightening torque for each screw is set to 3.7 N·m. During operation, it is necessary to ensure that all screws are tightened gradually in equal increments before reaching this torque to avoid premature clamping stress at any position, which could lead to deformation.

[0065] In addition, to verify whether the locking operation causes deformation of the part, the end face runout dial gauge test in steps S231 and S233 must be performed before and after symmetrical locking. The test position is part F. If the difference between the measured values ​​before and after is not greater than 0.01mm, it is considered that no unacceptable clamping deformation was caused during the locking process, and the formal processing stage can be entered.

[0066] After the part and fixture 1 are installed and fixed in step S200, and before proceeding to step S300 for machining, a crucial accuracy check operation is required: the runout of the check hole 2 on fixture 1 is adjusted. The purpose of this process is to ensure that the coaxiality between the overall installation state of fixture 1 and the spindle rotation center meets the machining requirements, providing a stable and reliable geometric reference for the subsequent high-precision grinding of the eccentric area.

[0067] Specifically, the operator uses a dial indicator to contact the indicator head with the inner wall of the calibration hole 2 of fixture 1, and measures the runout value point by point along the 360° circumference while the machine tool rotates at low speed. The runout is calculated by reading the difference between the highest and lowest points. If the runout exceeds the preset range set in the process specification (e.g., runout not greater than 0.005mm), it is necessary to repeatedly calibrate by adjusting the mounting posture of fixture 1 on the spindle or fine-tuning the clamping state until the runout value is within the allowable tolerance range.

[0068] In step S300, the processing of the target processing area adopts a phased progressive processing strategy, which includes three stages: roughing, semi-finishing and finishing, in order to achieve high-precision and low-deformation grinding control of the eccentric target arc segment.

[0069] The core principles of this multi-stage machining process are: gradually reducing the single machining load, minimizing thermal stress and rigid response impact, and improving dimensional convergence. Therefore, in the three stages, the feed rate and part speed in the machining parameters show a significant decreasing trend, while the grinding wheel linear speed remains constant throughout the entire machining process, for example, at 25 m / s, to ensure stable grinding conditions and controllable surface roughness.

[0070] Specifically: the roughing stage is mainly used to quickly remove excess material. In this stage, a larger feed rate and a higher rotation speed are used to form a rough profile that is close to the target size, while providing a uniform base allowance for the next stage; the semi-finishing stage further refines the profile based on the roughing stage, using a medium feed rate and a medium rotation speed, with the aim of reducing dimensional errors, controlling profile deviations, and gradually approaching the target size; the finishing stage completes the final grinding with a small feed rate and a low rotation speed to ensure the quality of the machined surface and dimensional accuracy.

[0071] For example, in a specific embodiment: the roughing feed rate is 0.02 mm / min, and the rotation speed is 100-120 r / min; the semi-finishing feed rate is 0.01 mm / min, and the rotation speed is 80-100 r / min; the finishing feed rate is 0.005 mm / min, and the rotation speed is 60-80 r / min; the grinding wheel linear velocity remains unchanged at 25 m / s in all stages.

[0072] By employing the segmented machining strategy described above, it is possible to effectively address issues such as uneven cutting loads and insufficient local rigidity in eccentric structures while balancing removal efficiency and machining stability. This ensures that the eccentric arc segment achieves the machining objectives of controllable dimensions, good surface quality, and dimensional accuracy. This method is particularly suitable for ring-shaped parts that cannot be machined through holes, have significant local eccentricity, and require control of runout and deformation.

[0073] After finishing to the target size in the final stage of step S300, the machining process does not end immediately. Instead, post-processing is performed by stopping the feed and continuing grinding for a preset time. The core purpose of this operation is to further stabilize dimensional accuracy, improve surface quality, and reduce dimensional springback or contour errors caused by residual stress.

[0074] Specifically, after the target machining area is machined to the theoretical target diameter D through finishing feed, the system stops the feed motion. At this time, the contact state between the grinding wheel and the workpiece remains unchanged, and a constant part rotation speed (e.g., 60-80 r / min) and grinding wheel linear speed (e.g., 25 m / s) are maintained. Short-term grinding friction is performed under conditions without active material removal. In this embodiment, the continuous grinding time is set to be no less than 30 seconds, which can be set by the CNC system or executed manually by timing. This period can effectively release the micro-stress concentration introduced by the previous machining, so that the surface of the machined area tends to a geometrically stable state without the disturbance of additional load, thereby significantly improving the repeatability and measurement consistency of the final machined dimensions.

[0075] In step S400, to achieve high-precision detection and determination of the actual diameter of the eccentric arc segment of the target machining area, at least one calibration line is provided on the inner wall of the calibration hole 2 of the fixture 1. This calibration line corresponds to the standard contact position of the dial indicator head under the theoretical target diameter D. The calibration line is usually formed by laser etching or precision mechanical grooving, and its position is precisely calibrated on a virtual circle coaxial with the target eccentric diameter, with the rotation center of the fixture 1 as the reference. The function of this calibration line is to provide a reference for reference when using a dial indicator for drag testing.

[0076] To accurately measure the actual diameter of the target machining area under the eccentric structure, step S400 employs a detection strategy combining the calibration hole 2 of fixture 1 with a dial indicator dragging method. The process includes the following specific steps:

[0077] S410, Dial Indicator Zeroing: The operator lightly touches the dial indicator head to the inner wall of the calibration hole 2 of fixture 1 and sets the dial indicator reading to "0", completing the initial reference position calibration. Since the inner diameter of calibration hole 2 is consistent with the theoretical diameter D of the target machining area, the "0" position at this moment is the reference value corresponding to the theoretical diameter D.

[0078] S420, Measuring the eccentric arc segment: After zeroing, keep the fixture 1 and the part fixed, and slowly move the dial indicator along the axial direction of the fixture 1, so that its head smoothly transitions from the position of the calibration hole 2 to the machining surface of the target machining area of ​​the part. At this time, the dial indicator pointer deflects, and its displayed value A represents the radial deviation between the target machining surface of the part and the theoretical diameter surface.

[0079] S430, Calculate the actual diameter: Based on the dial indicator reading A, calculate the actual diameter D1 of the target machining area using the formula D1 = D + 2A. Where D is the diameter of the calibration hole 2 of fixture 1 (i.e., the theoretical target diameter), and 2A represents the cumulative amount of deviation on both sides in the diameter direction. If A is positive, it indicates that the machining area is larger than the theoretical value; if A is negative, it indicates that the machining area is smaller than the theoretical value.

[0080] Based on the actual data in this embodiment, the judgment criteria are as follows: If the dial indicator reading is 0.01 mm higher than the calibration mark, the actual diameter of the target processing area can be determined to be D1 = 237.66 + 2 × 0.01 = 237.68 mm; if the dial indicator reading is 0.005 mm higher than the calibration mark, the actual diameter of the target processing area is D1 = 237.66 + 2 × 0.005 = 237.67 mm; if the reading is 0 mm, the processing surface is completely consistent with the theoretical size, which is 237.66 mm.

[0081] Furthermore, before eccentric grinding, it is necessary to ensure that the original inner hole of the part is machined to a full circumference of φ237.676, and that the profile is less than the final requirement of |d|0.05|A|BB|. Currently, the machining setting requirement is |d|0.02|, which is guaranteed by grinding. Simultaneously, the dimensions and |j|φ0.02|A| of the three evenly distributed holes φ7 (+0.047, +0.025) on the part must be guaranteed, as well as their relative dimensions and the requirement of |d|0.05|A|BB| to the inner hole. These three holes serve as the center reference for eccentric grinding, which is guaranteed by precision boring. Only after these two aspects are machined to a satisfactory standard can the eccentric grinding process be completed according to the method of this patent.

[0082] This solution achieves high-precision machining control of thin-walled ring-shaped parts with eccentric structures by constructing an eccentric correspondence between fixture 1 and the target machining area. Its core principle lies in using multiple pre-set positioning holes 3 on fixture 1 to form a fitting circle. The center of this fitting circle has an offset from the rotation center of fixture 1 that matches the eccentric structure of the part. This ensures that after the part is clamped through the positioning reference hole 4, the geometric center of its target machining area coincides precisely with the rotation center of the machine tool spindle. Combined with the calibration hole 2 of fixture 1 and the dial indicator, real-time dimensional detection of the eccentric arc segment is also possible. Through this one-to-one mapping of the eccentric structure in the tooling design and the closed-loop control of the dial indicator measurement, not only is the problem of difficulty in locating the eccentric direction and center solved, but also stable clamping, precise machining, and online detection of the eccentric area are achieved, ensuring the measurability, controllability, and repeatability of the entire process chain.

[0083] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for machining thin-walled ring-shaped parts, used for machining parts where the center of rotation is eccentric to the geometric center of the target machining area, characterized in that, include: S100, prepare fixture (1), process verification hole (2) and multiple positioning holes (3) on fixture (1), verification hole (2) is coaxial with the rotation center of fixture (1), and the diameter of verification hole (2) is consistent with the target diameter D of the target processing area. The centers of multiple positioning holes (3) are enclosed to form a fitting circle. The center of the fitting circle is offset from the rotation center of fixture (1), and the offset value of the fitting circle is the same as the offset value between the rotation center of the part and the geometric center of the area to be processed. S200, fix the part on the fixture (1). The part is provided with multiple positioning reference holes (4). The centers of the multiple positioning reference holes (4) are distributed on a circle with the rotation center of the part as the center. Align the positioning reference holes (4) of the part with the positioning holes (3) of the fixture (1) so that the geometric center of the target processing area of ​​the part coincides with the rotation center of the fixture (1). S300 processes the target processing area using preset parameters; S400, perform dial indicator testing, and determine the actual diameter of the target machining area based on the difference between the dial indicator value of the target machining area of ​​the part and the calibration hole (2) of the fixture (1).

2. The processing method for thin-walled ring-shaped parts with eccentric structures according to claim 1, characterized in that: Step S400 includes the following steps: S410, bring the dial indicator head into contact with the inner wall of the calibration hole (2) to zero the dial indicator; S420, move the dial indicator along the axial direction of the fixture (1) so that the dial indicator head contacts the target machining area of ​​the part and read the dial indicator reading A; S430, calculate the actual diameter D1 of the target processing area according to the formula D1=D+2A.

3. The processing method for thin-walled ring-shaped parts with eccentric structures according to claim 1, characterized in that: In step S200, fixing the part onto the fixture (1) includes the following steps: S210, Align the part positioning reference hole (4) with the positioning hole (3) of the fixture (1); S220, a positioning pin (5) is inserted into the positioning reference hole (4) of the part and the positioning hole (3) of the fixture (1). The mating part of the positioning pin (5) and the positioning hole (3) is a cylindrical surface, and the mating surface of the positioning pin (5) and the positioning reference hole (4) is a conical surface. S230, using multiple locking screws (6) to lock the part onto the fixture (1).

4. The processing method for thin-walled ring-shaped parts with eccentric structures according to claim 3, characterized in that: Step S230 includes the following steps: S231, Perform dial gauge measurement on the end face of the part before locking; S232, multiple screws are tightened in a symmetrical tightening sequence; S233, after locking, measure the end face of the part again using a dial indicator and compare the measurement difference before and after locking. If the difference is not greater than the preset maximum allowable end face deformation, proceed to the next step.

5. The method for processing thin-walled ring-shaped parts with eccentric structures according to claim 4, characterized in that: In step S232, multiple screws are tightened in a symmetrical locking sequence. This means that a pair of screws at symmetrical positions are selected and tightened in sequence with the rotation center of the clamp (1) as the reference center. Then, the screws are gradually extended to the untightened screws (6) in an angularly even manner until all screws are tightened in a symmetrical sequence.

6. The method for processing thin-walled ring-shaped parts with eccentric structures according to claim 1, characterized in that: In step S300, the processing of the target processing area includes multiple stages, namely roughing, semi-finishing and finishing. The feed rate and part rotation speed parameters of roughing, semi-finishing and finishing decrease sequentially. Throughout the entire process of step S300, the grinding wheel linear speed remains constant.

7. The method for processing thin-walled ring-shaped parts with eccentric structures according to claim 1, characterized in that: The offset in step S100 includes angular offset and radial distance offset; In step S200, one positioning reference hole (4) of the part is marked as an angular reference hole, and one positioning hole (3) of the fixture (1) is marked as an angular reference hole. The angular reference holes of the part and the fixture (1) are coaxial to achieve angular offset matching.

8. The method for processing thin-walled ring-shaped parts with eccentric structures according to claim 1, characterized in that: After step S200 and before step S300, the method further includes: adjusting the runout of the verification hole (2) of the fixture (1) so that the runout of the verification hole (2) is controlled within a preset allowable range.

9. The method for processing thin-walled ring-shaped parts with eccentric structures according to claim 6, characterized in that: In step S300, after finishing to the target size, the feed is stopped and grinding continues for a preset time.

10. The method for processing thin-walled ring-shaped parts with eccentric structures according to claim 2, characterized in that: The calibration hole (2) of the fixture (1) is provided with calibration lines for use with a dial indicator for drag testing.

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